Abstract

The present study investigated the risk associated with concentrations of lead and cadmium in tissues (gills, livers and muscles) of Blackchin tilapia (Sarotherodon melanotheron) from upstream and downstream regions of an intertidal creek in Rivers State, Nigeria. The trend of Cd in fish tissues and water was as follows: muscle > liver > gills > water. The concentration of Cd in fish gills was higher in downstream fish when compared to upstream fish. The mean Cd-mg kg (-1) in fish gills was 0.048 +/- 0.015(-)upstream and 0.549 +/- 0.152-downstream, 0.037 +/- 0.030-upstream and 0.769 +/- 0.100-downstream, 0.026 +/- 0.015-upstream and 0.902 +/- 0.118-downstream, and 0.040 +/- 0.018-upstream and 0.727 +/- 0.157-downstream in December, January, February and March respectively. The trend of Pb in fish tissues and water was as follows: muscle > liver > gills > water. Pb was generally higher in fish sampled downstream when compared to those sampled upstream of the creek. Fish gills in upstream fishes had Pb of 6.324 +/- 0.388 mg kg(-1), 5.140 +/- 1.249 mg kg(-1), 5.459 +/- 0.471 mg kg(-1) and 5.730 +/- 0.859 mg kg(-1) while downstream fishes had Pb 7.732 +/- 0.640 mg kg(-1), 9.401 +/- 0.711 mg kg(-1), 7.575 +/- 0.624 mg kg(-1) and 7.644 +/- 0.637 mg kg(-1) in December, January, February and March respectively. Cd-fish gills Food and Agriculture Organization (FAO) maximum permissible limit (MPL), Cd-fish muscles and Cd-livers MPL for FAO, FAO/WHO and WHO. Pb-gills upstream and downstream > MPL for FAO, FAO/WHO and WHO. Pb and Cd did not indicate non-carcinogenic risks to human health owing to the consumption of fish up- and downstream. In the present study, fishes sampled upstream showed low cancer risk in adults, however, cancer risk index (CRI) indicated moderate cancer risk in children (male and female). For fishes sampled downstream, CRI indicated low risk for adults and male children, but a moderate risk for female children.